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Systems composed of several multi-layer compounds have been extremely useful in tailoring different quantum physical properties of nanomaterials. This is very much true when it comes to semiconductor materials and, in particular, to heterostructures and heterojunctions. The formalism of a position-dependent effective mass has proved to be a very efficient tool in those cases where quantum wells emerge either in one or two dimensions. In this work, we use a variety of mathematical theorems, as well as numerical computations, to study different scenarios pertaining to choices of a specific piecewise constant effective mass for a particle that causes its energy eigenvalues to reach an extremum. These results are relevant when it comes to practical technological applications such as modifying the optical energy gap between the first excited state and the ground state energy of the system. At the end of our contribution, we also question the physical validity of some approximations for systems with particles that possess a position-dependent mass especially for those cases in which the mass distribution is divergent.
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http://dx.doi.org/10.3390/nano14221850 | DOI Listing |
J Phys Chem A
September 2025
Department of Physics, University of Oxford, Oxford OX1 3PJ, U.K.
We derive the coupled-cluster doubles (CCD) amplitude equations by introduction of the particle-hole-time decoupled electronic self-energy. The resulting analysis leads to an expression for the ground-state correlation energy that is exactly of the form obtained in coupled-cluster doubles theory. We demonstrate the relationship to the ionization potential/electron affinity equation-of-motion coupled-cluster doubles (IP/EA-EOM-CCD) eigenvalue problem by coupling the reverse-time self-energy contributions while maintaining particle-hole separability.
View Article and Find Full Text PDFJ Phys Chem A
September 2025
Deparment of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark.
Based on a theoretical analysis of systems composed of subsystems described using a coupled cluster parametrization, we developed a vibrational coupled cluster embedding theory specifically tailored for the computation of response properties. This work identifies several strategies for calculating excitation energies, transition probabilities, and other response functions in large systems of interacting subsystems. A particularly effective embedding approach was formulated around a Lagrangian with multilinear interaction terms, yielding a structure that is nonlinear in both coupled cluster amplitudes and multipliers.
View Article and Find Full Text PDFPhys Chem Chem Phys
September 2025
Department of Chemistry and Sustainable Technology, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, FI-80100, Joensuu, Finland.
Accurate thermodynamic calculations for aluminum alkyls require proper treatment of low-frequency vibrations poorly described by the harmonic approximation (HA). Here, we present a systematic investigation of hindered rotation and out-of-plane bending in aluminum trichloride (ATC) and its methyl derivatives, employing advanced computational methods to perform anharmonic entropy corrections, such as torsional eigenvalue summation (TES), the extended two-dimensional torsion method (E2DT), the multi-structural approximation with torsional anharmonicity (MS-T), and Fourier grid Hamiltonian (FGH). Our results reveal distinct structure-dependent behaviors: monomers exhibit near-free methyl rotations where the HA overestimates entropy by 20-30 J K mol, while dimers show more hindered rotations adequately described by the HA around room temperature.
View Article and Find Full Text PDFBrief Bioinform
August 2025
Department of Computer Science, Ben-Gurion University of the Negev, David Ben-Gurion Blvd. 1, Beer-Sheva 8410501, Israel.
Hepatitis delta virus (HDV) is geographically classified according to eight known genotypes. The combined hepatitis B-hepatitis D (HEPB-HEPD) disease is the severest form of chronic viral hepatitis in humans and is characterized by mortality rates of ~20%. Hepatitis delta virus has no FDA approved therapy and its only available vaccine is the one for HEPB.
View Article and Find Full Text PDFJACS Au
August 2025
Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
Accurate prediction of reaction energetics remains a fundamental challenge in computational chemistry, as conventional density functional theory (DFT) often fails to reconcile high accuracy with computational efficiency. Here, we introduce Deep post-Hartree-Fock (DeePHF), a machine learning framework that integrates neural networks with quantum mechanical descriptors to achieve CCSD-(T)-level precision while retaining the efficiency of DFT to solve the reaction problems. By establishing a direct mapping between the eigenvalues of local density matrices and high-level correlation energies, DeePHF circumvents the traditional accuracy-scalability tradeoff.
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